/*
 * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.swing.colorchooser;

final class ColorModelHSL extends ColorModel {

  ColorModelHSL() {
    super("hsl", "Hue", "Saturation", "Lightness", "Transparency"); // NON-NLS: components
  }

  @Override
  void setColor(int color, float[] space) {
    super.setColor(color, space);
    RGBtoHSL(space, space);
    space[3] = 1.0f - space[3];
  }

  @Override
  int getColor(float[] space) {
    space[3] = 1.0f - space[3];
    HSLtoRGB(space, space);
    return super.getColor(space);
  }

  @Override
  int getMaximum(int index) {
    return (index == 0) ? 360 : 100;
  }

  @Override
  float getDefault(int index) {
    return (index == 0) ? -1.0f : (index == 2) ? 0.5f : 1.0f;
  }

  /**
   * Converts HSL components of a color to a set of RGB components.
   *
   * @param hsl a float array with length equal to the number of HSL components
   * @param rgb a float array with length of at least 3 that contains RGB components of a color
   * @return a float array that contains RGB components
   */
  private static float[] HSLtoRGB(float[] hsl, float[] rgb) {
    if (rgb == null) {
      rgb = new float[3];
    }
    float hue = hsl[0];
    float saturation = hsl[1];
    float lightness = hsl[2];

    if (saturation > 0.0f) {
      hue = (hue < 1.0f) ? hue * 6.0f : 0.0f;
      float q = lightness + saturation * ((lightness > 0.5f) ? 1.0f - lightness : lightness);
      float p = 2.0f * lightness - q;
      rgb[0] = normalize(q, p, (hue < 4.0f) ? (hue + 2.0f) : (hue - 4.0f));
      rgb[1] = normalize(q, p, hue);
      rgb[2] = normalize(q, p, (hue < 2.0f) ? (hue + 4.0f) : (hue - 2.0f));
    } else {
      rgb[0] = lightness;
      rgb[1] = lightness;
      rgb[2] = lightness;
    }
    return rgb;
  }

  /**
   * Converts RGB components of a color to a set of HSL components.
   *
   * @param rgb a float array with length of at least 3 that contains RGB components of a color
   * @param hsl a float array with length equal to the number of HSL components
   * @return a float array that contains HSL components
   */
  private static float[] RGBtoHSL(float[] rgb, float[] hsl) {
    if (hsl == null) {
      hsl = new float[3];
    }
    float max = max(rgb[0], rgb[1], rgb[2]);
    float min = min(rgb[0], rgb[1], rgb[2]);

    float summa = max + min;
    float saturation = max - min;
    if (saturation > 0.0f) {
      saturation /= (summa > 1.0f)
          ? 2.0f - summa
          : summa;
    }
    hsl[0] = getHue(rgb[0], rgb[1], rgb[2], max, min);
    hsl[1] = saturation;
    hsl[2] = summa / 2.0f;
    return hsl;
  }

  /**
   * Returns the smaller of three color components.
   *
   * @param red the red component of the color
   * @param green the green component of the color
   * @param blue the blue component of the color
   * @return the smaller of {@code red}, {@code green} and {@code blue}
   */
  static float min(float red, float green, float blue) {
    float min = (red < green) ? red : green;
    return (min < blue) ? min : blue;
  }

  /**
   * Returns the larger of three color components.
   *
   * @param red the red component of the color
   * @param green the green component of the color
   * @param blue the blue component of the color
   * @return the larger of {@code red}, {@code green} and {@code blue}
   */
  static float max(float red, float green, float blue) {
    float max = (red > green) ? red : green;
    return (max > blue) ? max : blue;
  }

  /**
   * Calculates the hue component for HSL and HSV color spaces.
   *
   * @param red the red component of the color
   * @param green the green component of the color
   * @param blue the blue component of the color
   * @param max the larger of {@code red}, {@code green} and {@code blue}
   * @param min the smaller of {@code red}, {@code green} and {@code blue}
   * @return the hue component
   */
  static float getHue(float red, float green, float blue, float max, float min) {
    float hue = max - min;
    if (hue > 0.0f) {
      if (max == red) {
        hue = (green - blue) / hue;
        if (hue < 0.0f) {
          hue += 6.0f;
        }
      } else if (max == green) {
        hue = 2.0f + (blue - red) / hue;
      } else /*max == blue*/ {
        hue = 4.0f + (red - green) / hue;
      }
      hue /= 6.0f;
    }
    return hue;
  }

  private static float normalize(float q, float p, float color) {
    if (color < 1.0f) {
      return p + (q - p) * color;
    }
    if (color < 3.0f) {
      return q;
    }
    if (color < 4.0f) {
      return p + (q - p) * (4.0f - color);
    }
    return p;
  }
}
